1. Field of the Invention
The invention relates to an annular combustor arrangement. In particular it concerns the fuel supply manifold arrangements for a staged combustor.
2. Description of Related Art
It is now common practice in gas turbine engine combustion chamber design to use multiple combustion zones, ie fuel staging, for dual improvements of controlling exhaust emissions and enabling the combustor to operate over a wide range of air/fuel ratios. It follows therefore, since there are normally separate arrays of fuel injectors for each combustion stage, that this type of combustor employs more fuel injectors than a conventional non-staged combustor. The corresponding fuel manifolds and supply pipe work, following conventional design practice, are mounted externally of the combustion chamber outer casing and each fuel injector is connected individually to its associated fuel manifold by radially extending fuel conduits passing through the combustion chamber walls. A drawback with such a combustor arrangement is its intrinsically heavy weight.
A further drawback arises in a bypass engine where the fuel manifolds are located within the bypass duct. Consequently the fuel manifolds are subjected to aerodynamic buffeting and heat transfer of the fan bypass airflow, and are susceptible to impact damage arising from foreign object ingestion at the front of the engine.
The present invention seeks to avoid these disadvantages and to provide a lighter arrangement with improved damage resistance.